Study Of SiC Surface Passivation Using First-principles Thermodynamics

As the third-generation semiconductor material, SiC is gradually replacing Si by its virtue of wide band gap, high critical breakdown voltage, high thermal conductivity and saturated drift velocity and become the fundamental material to produce high-temperature, high-pressure, high-power semiconductor devices. SiC, compared to Si, could meet the requirements of modern electronic technology to the new requirements of the harsh conditions of high temperature, high-power, high-voltage, high-frequency and anti-radiation, and has a very broad application prospects. However, due to the higher SiO2/SiC interface state which causes the MOSFET channel mobility is seriously hindered the realization of the many functions of the SiC device, the surface washing, interface state density for reduce SiO2/SiC the further application of the SiC material play a very critical role.This article is based on first-principles thermodynamics, we select4H-SiC (0001) surface for research, which focus on SiC wet cleaning, surface hydrogen and hydroxyl distribution and competitive adsorption relations and gas annealing P passivation of SiC surface situation research, trying to find in both cases, the SiC surface adsorption configuration of the most stable configuration, which will play a theoretical guidance for the actual SiC material application. In this study,we use the VASP software and CASTEP package in the Material Studio software, built SiC original package to optimize the calculation, adsorption the different adsorption surface passivation case of the formation energy and surface free energy by the chemical potential and the adsorption energy and free energy relationship, and draw chemical potential phase diagram, stable configuration of the electronic structure analysis.The results of this study indicate that, the H passivation after wet cleaning and passivation OH, when there is only adsorption of H, SiC surface is a single adsorption advantageously、4H adsorption advantageously and wholly favorable adsorption; for only adsorption of OH, SiC surface is a single adsorption beneficial, wholly favorable adsorption, adsorption of H and OH at the same time, we can see the most stable configuration in SiC surface Adsorption phase diagram analysis. And the most stable configuration for passivated P is1/3coverage energy. This study can be useful in the actual SiC materials processing and production of the device applications, and facilitates to lower surface of the interface state density, improve the quality of the interface, optimize and improve the performance of the material, and provides a useful theoretical basis and guidance.